Language performance is the area of greatest difficulty for American Indian children in school settings. The incidence and prevalence of speech and language disorders are substantially higher in the American Indian population than for other ethnic groups. Language difficulties are greatly influencing their success in the educational systems, yet, there are presently few valid measures of language development for use with the American Indian bilingual child. Measures of normal development in the American Indian bilingual child would allow more accurate assessments of their language performances and facilitate the identification of language disorders. Accurate, valid diagnostic language tasks are sorely needed for this population if the special education and related services efforts are to be effective. The purpose of this research is address both empirical needs and student training in the area of language development research. The training purpose of this study is to develop the research skills of at least four Native American University student in the area of language acquisition. These student research assistants will participate in (1) the development of appropriate data collection protocols and procedures, (2) training of personnel for data collection, (3) data collection, (4) data reduction, (5) data analysis, (6) data interpretation, (7) manuscript preparation, and (8) professional presentation of the research. The empirical purpose of this study is to develop a standardized developmental language measure for bilingual Navajo-English children between the ages of six and sixty months using the Sequenced Inventory of communicative Development-Revised (SICD-R) (Hedrick, Prather, & Tobin, 1986). A total of 300 Navajo children will be administered both the Navajo and English version of the SICD-R.